Formulation of guava (Psidium guajava)-based boric acid-ATSBs and molecular docking of guava volatiles with AeOBP22 odorant binding protein of Aedes aegypti

Widespread insecticide resistance and persistent burden of vector-borne diseases demand the development of novel, eco-friendly mosquito control methods. The study formulated and evaluated the potential of Attractive Toxic Sugar Baits (ATSBs) against the dengue vector, Aedes aegypti . Initial assays identified a suitable attractant to formulate an effective ASB followed by formulation of an ATSB. Attractancy assays were held with fermented guava, pear and plum juice added with sucrose as feeding stimulant. The results identified guava-ASB with maximum attractant potential. Thereafter, dose-response toxicity bioassays were held using boric acid as a toxicant in the formulated ATSB which established a linear dose-dependent mortality, ranging from 8.00% at 0.2 mg/5 mL to a significant 98.00% at 6.4 mg/5 mL against Ae. aegypti . Major volatile constituents of guava were identified through a comprehensive review of previously published GC–MS studies, and five abundantly reported compounds; β-caryophyllene, Nerolidol, β-pinene, Eucalyptol (1,8-cineole) and Ethyl hexanoate; were selected for analysis. These volatiles were docked with a transporter odorant-binding protein 22 (AeOBP22) using AutoDock Vina. Their binding affinity was compared with two control volatiles, arachidonic acid and linoleic acid, known to show strong affinity with AeOBP22. It revealed β-caryophyllene exhibiting the highest, though moderate binding affinity toward AeOBP22, better than the controls. These findings suggest that specific guava-derived volatile compounds may play a significant role in attracting mosquitoes through AeOBP22 which carries these volatiles to the concerned receptor. This study provides a molecular basis for the use of guava-based ATSB formulations as cost-effective, efficacious and sustainable intervention tool in the global fight against mosquito-borne diseases. Field and more extensive studies may determine the mechanism involved helping in making a long-term, stable formulation against Ae. aegypti.